Plasterboard walls can absorb bass frequencies yet reinforce higher frequencies causing them to reflect round the room. This makes it difficult to achieve a flat response. Acoustic treatment the only solution.
Play a 120htz tone and see if you can hear it solidly at the listening position, you may be sitting in a null area.
…also. The most obvious explanation is that the speaker cables, when connected to the 250, are reversed. Turn the 250 off and swap one set of cables going into one speaker, i.e the one in + into - and visa versa - switch back on any improvement?
Not Ohm’s law above all! Whilst knowledge of Ohm’s law has some real use, e.g. calculating voltage drop, in practical terms in most domestic installations in UK with its high mains voltage voltage drop is rarely of any great significance. What is far more important is knowledge of heat rise in cables for whatever is the maximum load before tripping of the breaker, taking into account the routing and means of fitting (e.g. whether in conduit, clipped to a surface, running through thermal insulation, etc), together with the maximum ambient temperature wherever they run (e.g. in a loft), and the thermal limit of the cable insulation. This information determines the minimum safe cable size for use with the breaker.
So much better sound but the same lack of bottom end. Either the room is beyond bad accutically, the power is somehow surge protected in the building (which kills the sound) or the power amp got damaged during transport from overseas. (it tripped the power again today, after resetting the fuse from the wall fusebox it started normally). Will try to bring another Naim power amp in the house and test it against mine.
Anyway, many thanks to Marek from Denis White.
Just to recap: you moved home. Different room, nearly twice the size and with, as you describe them, cardboard walls instead of brick.
Those are very fundamental differences, and yet although some responders have suggested the room, it seems all the focus has been on the power supply, and questioning whether the amp is OK. Whilst I understand that the comparison with the Cyrus is part of what makes you suspect the amp, and there is certainly no harm at all in trying to borrow another amp to verify, it seems to me that the elephant in the room is still the room itself.
In my original response I suggested if possible trying in another room in the flat as similar as possible in dimensions to your old listening room, which would give you an idea of the effect purely of room size, though not construction. (That could still be something worth doing, despite the hassle.) And the construction of the walls may be very significant, as they could be far more absorbing at the bass end than your old walls. Quite what the solution is if it is indeed the room is harder to fathom. I find descriptions of Naim amps at the bass end odd, as their specs don’t indicate any difference, but people seem to experience greater bass extension (as opposed to just better bass control) as you go up the range, but whatever the reason, if that is the case the greater bass drive needed in the bigger room with absorbent walls might need an amp with greater bass ability than the 250.
However you have now changed speakers, though with no information as to how you chose the Dynaudios and how you know they suit your taste and room. (if you had talked about changing speakers people likely would have suggested trying at home, when you could be sure that whatever you bought would work.) The new speakers presumably have better bass capability than your old ‘bookshelf’ speakers (I don’t recall what they were), which might be expected to give you a better chance in the bigger room.
That brings me to the crux: re-reading the thread, you haven’t talked at all about experimenting with room layout, notably speaker and listening positions, yet they can make a huge difference. If I were you I would get a copy of REW (“Room Equalisation Wizard”) software, which is available free of charge, and a measuring microphone (the one REW recommend is good and relatively inexpensive), and do some room measurements to start to find out what is going on in the room, and play with positioning. There is another current thread with someone exploring speaker positioning, which may give some food for thought. (What do you think? Speaker placement advice)
IB: Ill be reading your reply more than a couple of times Im sure. Really appreciate the time and effort you have put in it.
My former speakers were elac 244be. And while I understand the logic behind playing with positioning, both listening and speakers themselfs, I have moved quite a bit in the last couple of years and I know my naims. This is something much more serious than just a nuance. Its almost as if I would power my gear through an UPS.
Ill try borrowing a power amp and test it against mine. Although the ideal test would be with another 250dr.
The sound is more refined, relaxed and easier to listen to than it was with the elacs, and all this from a cold start. Once burned in, the gap should be considerably wider.
HH tells me in another thread my shelfs are upside down and reversed, something that perhaps will get addressed sometime in the future. Dont think thats the culprit for my misfortunes.
Thanks again for your valuable input IB.
Indeed - and the effect of rooms and positioning can be far more than a nuance, potentially far greater than almost any other factor, though I anticipate the Dyns should be far more capable at the bass end than the Elacs.
By way of example, I used to have a pair of IMF RSPM speakers - proper full range speakers - in a variety of rooms from 16’x12’ to 24’x14’, always with reasonable success at first positioning, only needing slight tweaking. Then I moved into my current house, with an oddly shaped room about 24’ x 24’ overall, and at first setup the bass had completely disappeared - completely cancelled in the vicinity of the planned listening position. Nothing I tried worked. Things were so bad I got myself a copy of REW and started exploring the room - and ended up completely rethinking room layout, original planned speaker-listening position arrangement rotated by 90 degrees, and was back in business, and after tweaking, assisted by REW, everything came together nicely.
So, good luck with yours - hopefully you will resolve to your satisfaction in due course.
Still, all this isn’t as bad as if you had moved the hifi and the house collapsed.
A real probability going by the looks of some hifi encouraged these days.
As I mentioned previously I had pretty much the exact same problem that you did after moving house. After I put in the room treatments my wife just needed to listen to a few tracks to remark “ that’s way above any improvement you’ve had by any change of boxes you’ve ever made”. I wasn’t the only one to be impressed. You owe it to yourself to make those REW measurements, use them to evaluate sitting ansd speaker positions as IB has said and then see what an acoustic treatment company makes of them.
The room is quite large but cant really move around anywhere…there are another 3m behind the point I took this pic from.
Could it be something physically wrong with either my pre or power amp? Went the other day to visit some friends and found myself taping in pleasure, listening to Spotify on a samsung bar with a plastic subwoofer.
Triple checked everything today, while rebuilding the rack as instructed by HH. 
Next, I would like to try powering the system from a socket in another room but other than that, I’m out of ideas.
Could be that your loading that particular corner of a large room with detrimental effects.
As you have the visual hub on a stand, you could try moving that more towards the right corner and having the right and left speaker hot spot firing more diagonally across your room - with the hot seat on that large sofa more to the left.
Moving that large sofa somewhat about a couple of feet to the left so there’s some exit path for compression sound waves.
Above is an image of my set up to give a rough idea.
If your sofa is dead centre front to back that is usually a bad position. Have you tried waling around the room while music playing to see what it sounds like in different places, with your speakers where they are, and with them moved out! If not then do try.
Other ideas:
Rotate everything 90 degrees and try (facing the window)
Rotate 180 degrees and try
Swap the current position with the near end of the room, and try al, the above.
Try a diagonal arrangement, with one speaker in front of one wall, and the other at right angles in front of another (“shouldn’t” work, but I know of one setup where it does).
And as I suggested, get a copy of REW and a microphone and actually see what is happening in tge room.
Before the Dynaudios, I had bookshelves that I know they had a monstrous amount of bass in any room, big or small. Once deployed in 'stralia, the sound went dead (powerless), hence my speedy upgrade to standfloors. It’s almost as if the woofers died. They are still moving…but not that much to be honest.
If the woofer cones are moving, but you don’t hear the bass, suspect room cancellation.
As for the amount they move, with its twin drivers of the same size as the Elac, the cones on the Dyns will only move half the distance of the Elac’s woofer cone for the same sound output.
Dan, great room, but it does look as if it would sound very ‘live’. Lots of hard reflective surfaces and not much in terms of soft furnishing etc apart from a rug and sofa. The room itself might be the problem?
There is a good discussion in this thread. I’ve moved my speakers with a big improvement in soundstage.
I strongly suspect that without either moving house or putting the system in a much smaller room, that you are just going to have to get used to the poor sound. No amount of tweaking mains or getting the shelves the right way up (!!) will compensate for the fact that the room is huge with hard surfaces everywhere and an opening on the wall where the speakers are. As soon as I saw that picture I thought ‘ah, so that’s why it sounds so gutless’. Whether significant room treatment would help I don’t know, as it’s something I have very little knowledge of.
In our smallish room 3.6m wide and just over 5m long, we have a concrete floor, concrete walls, heavy fire doors, carpet and a large stuffed sofa. With the doors shut and the volume up the system drives the room so you feel totally immersed. But looking at your room I can imagine a sound as if it’s just music coming from some speakers sitting at the end, with no engagement and no drive, just gutless.
So after all that, which is genuinely meant to be helpful, I’d say just get used to it, or put it in another room (and I can see why you wouldn’t want to do that) or move.
I tend to agree with that Nigel, I thought the same when I saw the room photograph. Dan, do you have an alternative room to see if you can get it working better? I know that is not ideal.
Stu
